This application relates to the art of controls and methods for operating electric water heaters. The invention is particularly applicable to a control and method that uses a control module running software and will be described with specific reference thereto. However, it will be appreciated that the invention has broader aspects and can be carried out with other types of controls.
An electric water heater energizes one or more heating elements located within the water heater tank to heat water. Electrical power to the heating elements is managed through the operation of a control module, which controls the opening and/or closing of electrical relays connected in series between a power source and the heating elements. The thermal energy generated by the heating elements dissipates in the water, thereby heating the water according to a desired or preset water temperature. The control module is operable to interrupt power to the heating elements by opening one or more of the electrical relays.
Certain circumstances may cause the heating elements to malfunction or burn out, causing an open circuit. When this occurs, the control module is unable to use the heating element to heat the water. Operation of the electric water heater with an open heating element may result in further damage to one or more additional components of the electric water heater. Therefore, it is desirable to detect an open heating element prior to providing power to the heating element.